Once I have the twin flown ... I am honestly considering a mild PKJ ! Yes a stock one .... the 222 one is stripped to bare frame now after too many crashes and repairs trying to beat her old record. The later PKJ2 is in good 'uncrashed' order but is the basis for my twin attempt, the 4400kv and stuff are benched.

So thoughts came round to whether I should hit what I term the max thr PKJ is capable of ... then relax to more sedate sub 200 speeds !!

Just to recap ........ Twin is :

2 of 3800kv 250 heli motors
2 of 4.1x4.1 and 4.5x4.5 contra props
2 of 50A ESC's with separate BEC
3S 1800 and a 4S 1500 ... first run with 3S .. then if successful - we hit it with the 4S ... short run time and possibly ESC's will be on limits ... but should be interesting.
No gyro ... but serious D/R + Expo to keep her tamed.

Calculations based on my data sheet of actual results on prev PKJ's indicates a possible speed of about 250kph with 3S and over 285kph with 4S ...

One aspect that is troubling is how to catapult ... it indicates a dead launch and only AFTER exit the rails to engage motors ... due to props striking rails if turning. This worries me because of 'panic' pushing stick fwd .. it would be too easy to push throttle too far too quick ... as it's only a matter of a second or two between exit rail and demand for power ...
I'm trying to figure out if I can design a wire cradle that lifts it enough to allow props to turn ... slide up the rails ... drop away without having prop strike ...
Initial thoughts are a cradle that is actually attached to the bungee ? That all models in fact could use ...

I used similar to this many years ago .... but now it wouldn't worjk for me as flight sites are rough ground.
I need to have something on the rails of the catapult launcher.
Second the PKJ needs to be at real speed before I can successfully control it ... something the catapult gives me.

I did consider a 4 wheel dolley without tyres ... running on the rails ... but actually a smooth frame is good enough ... just need to design it.

Nigel how's the PJ 2 coming along?
I am dieing in anticipation to see that beast.
AUSAELECTRIC
have a look at how I did mine.no work at all and to this day it's held up perfectly.and my PJ has had some hard meetings with mother earthhttp://www.rcgroups.com/forums/attac...mentid=4007087

Stuffed my PJ into the ground yesterday. Nose now bent up and motor stick mount ripped out. Some hot water treatment, two 6x1mm carbon flats and some CA and looks good as new.
I find one of these is ideal for enlarging the slot for the carbonhttp://www.ebay.co.uk/itm/Flush-Cut-...item5d35eddda1
Re-glued the motor stick and added a recessed lolly stick underneath which I then screwed through into the motor stick. I appreciate that if I have a hard landing the whole mount area will probably rip out as used to happen with the original Stryker. Build to fly not to crash.
Andy

I'd recommend stuffing a 1cm hollow carbon rod about 1/3 from the tip of the nose to about halfway back in the battery area.
if can be done by serrating the rod by dremelling a number of notches a few mm apart around the perimeter. Rotate the shaft like a drill would. Back it out, stick some Gorilla glue + water in the hole, and re-insert the rod. Once set, cut the front protruding rod off.
My PK is super stif and strong now. I have almost no fear of crashing now (I still would rather not).

Nigel how's the PJ 2 coming along?
I am dieing in anticipation to see that beast.
AUSAELECTRIC
have a look at how I did mine.no work at all and to this day it's held up perfectly.and my PJ has had some hard meetings with mother earthhttp://www.rcgroups.com/forums/attac...mentid=4007087

Get me out of China and I'll get her in the air !! Darn work assignment has dragged on ...

I'd recommend stuffing a 1cm hollow carbon rod about 1/3 from the tip of the nose to about halfway back in the battery area.
if can be done by serrating the rod by dremelling a number of notches a few mm apart around the perimeter. Rotate the shaft like a drill would. Back it out, stick some Gorilla glue + water in the hole, and re-insert the rod. Once set, cut the front protruding rod off.
My PK is super stif and strong now. I have almost no fear of crashing now (I still would rather not).

My way is to lay in two balsa spars underneath ... these not only are light and give rigidity with them and the epoxy, but also allow me to fix the velcro more securely to hold the LiPo in place.

i'v tried that more than once and this is what i get ......i copied this link from wattflyer and also off my utube channel and each time this is the result....would love to share the pkj4 vids here at rcg...theres a lot more experimenting on the pkj's here.